Caulk is a waterproofing material used by building contractors and homeowners for sealing windows, doors and bathtubs.
Caulk is most conveniently dispensed and applied using caulking guns, to which are fitted a plastic or cardboard tube containing caulk.
Two main types of caulking guns are known. The first is the bulk dispensing gun, which is a complete unit containing a closed cylindrical chamber with nozzle and actuating means. The second is the open framed cartridge gun, in which the gun itself and a disposable cartridge containing caulk comprise separate elements.
The open-framed cartridge gun typically comprises a cradle to receive a cartridge containing caulk, one end of the cartridge having a dispensing nozzle. A piston is provided within the cartridge. Caulk is dispensed by exerting pressure on a trigger of a pistol-grip mechanism, which actuates a push rod having a thrust disk at its front end. Pressure exerted by the thrust disk against the caulk cartridge piston forces caulking material out of the cartridge nozzle.
Many variations of the open-framed cartridge gun have been described in the art. In all of these, the push rod is at least as long as the cartridge, plus the distance the push rod must travel through the pistol-grip mechanism in order to be able to urge the thrust disk along the entire length of the cartridge. In addition, a small segment of the push rod must remain exposed after the cartridge has been depleted so that the exposed segment of the push rod can be grasped by hand and retracted to the starting position. The total length is further increased by the nozzle of the cartridge when full, resulting in a relatively long caulking gun. Such a device is awkward to handle and cannot easily fit into tight spaces such as cupboards, closets, behind doors etc.
In existing open-framed cartridge guns the cartridge is inserted by first retracting the push rod, then manually manipulating the cartridge into place. The cartridge is released by retracting the push rod while simultaneously pressing a release lever or button. These manipulations are awkward and time-consuming.
Therefore, it would be desirable to provide a cartridge caulking gun which is shorter and easier to manipulate than the prior art devices, and in which loading and removal of cartridges is simplified.